we are facing some trouble regarding the setpoint velocity send my mavros/mavlink.The guided velocity is not matching the desired velocity (see pictures below). Do you have any clue why this happens or how we could fix this? We was using Here+ RTK, Pixhawk 2.1 Cube and 3.5.3 firmware.

CN,I looks like it's trying to do what's been requested but it can't, this leads to it getting behind and it then overshoots. I think it would perform better if you more gradually increased the velocity request instead of immediately jumping it to 100.

To add some more background, when the velocity controller is used it actually also tries to maintain a position and this position comes from the integrated velocities. I suspect in the velocity controller we are not acceleration limiting the requested velocities so this naturally leads to bad behaviour when the velocity inputs are changed too rapidly.

Attached, 2 screenshots. One of our testflight yesterday and I got a screenshot from a DJI as comparison. For my understanding, it never comes to an overshoot but at the end of the guided command, the DJI is much more behind (more smooth) but more stable in holding the velocity.

@Amilcar: Could you please explain it more detailed about "take that acceleration into account"?

We are flying arducopter for several years, and we never had a crash/big error during flight. But we was never so in detail to find best response/tuning. But, for my opinion now, it is necessary! Hopefully we can get this rocking and I can write a tutorial/wiki for other peoples in the future.

We tried this before uploading the firmware and it was not working with the real copter. Which parameters did you changed exactly? We tried, Loiter P and I at minimal values and also with "0", it was not a different in Overshot but you could see with your eyes that it could not really correct the position before sending velocity.